On Fri, Nov 25, 2016 at 04:23:13PM +0200, Jarkko Oranen wrote: > I tried sending this to [email protected] first but it bounced. Is that > address no longer available?
It should still work, but I see the bounces also. I filed a ticket with the Linux Foundation to get it looked at. > I posted to ovs-discuss earlier about performance issues with OVS on CentOS 7. > See > <https://mail.openvswitch.org/pipermail/ovs-discuss/2016-November/043003.html> > > It seems we've found the culprit, and it's quite unexpected. Due to some > broadcast in our networks, OVS is at times receiving jumbo packets which cause > the following to appear in dmesg: > > [1991029.408139] openvswitch: qvo41ed92a6-50: dropped over-mtu packet: 8982 > > 1500 > [1991029.765021] openvswitch: qvofc43bfd2-9d: dropped over-mtu packet: 8982 > > 1500 > [1991031.021320] openvswitch: qvo41ed92a6-50: dropped over-mtu packet: 8982 > > 1500 > > On a host where the serial console speed is set to 115200, these log messages > print out fast enough that no significant harm is done, but on the hosts where > we had these issues, our serial console was misconfigured and very slow. This > seems to have affected OVS enough to cause network latency. > > After fixing the console settings, we're no longer experiencing the heavy > latencies, probably because it's now logging fast enough not to trigger bad > behaviour... > > Is there perhaps a way to avoid this issue altogether? I think that serial logging from a softirq, which is where OVS handles packets, is always going to happen synchronously, which means that it's going to be as slow as the serial connection. Here's an example of a similar issue: https://access.redhat.com/solutions/658783 Maybe someone else has a good idea, though; I'm no expert here. _______________________________________________ discuss mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-discuss
